U.S. Pat. No. 5,576,591 has already disclosed a lamp having a base at one end, which comprises three bulbs. It has a ceramic adapter which is mounted on a screw base. Atmospheric pressure prevails between the envelope bulb and the outer bulb.
U.S. Pat. No. 6,411,036 discloses a high-pressure lamp having a base at one end, in the case of which the outer bulb is surrounded by a reflector. The base is fixed directly to the reflector neck by means of crimping. One disadvantage of this is the fact that the dimensions of the neck of the reflector must be matched to the standard dimensions of the base.